FIELD OF THE INVENTION
The field of the invention is cleaning apparatus for cleaning carriers used to hold and process semiconductor wafers, substrates, flat panel displays and similar flat articles requiring low contamination levels.
The processing of semiconductor wafers, substrates, photomasks, flat panel displays, data disks, and other articles relating to the semiconductor industry (collectively referred to as "wafers") is very sensitive to problems of contamination. These articles require extremely low contamination levels. Even tiny contaminants can cause defects. Accordingly, it is necessary to maintain a high level of cleanliness during virtually all stages of manufacture.
Semiconductor wafers are typically processed in batches. Batch handling may occur throughout the entire production process, or for one or more processing steps or related handling operations. Batch processing almost always uses some type of carrier to hold the wafers. The wafer carriers can be of various designs. Carriers in the form of a protective case or box are often used. In these types of carriers, the wafers are held and enclosed against contamination during travel within the processing facility. The wafer carriers must be cleaned, to avoid having particles and contaminants on the carriers contaminate the wafers. However, cleaning wafer carrying boxes can be difficult because they typically have features such as slots, grooves or apertures.
One type of wafer carrier is known as the front opening unified pod, or FOUP. A FOUP carrier has a five-sided box with an open front. A door attaches to the front of the box, to seal the box against entry of external contaminants, to help keep the wafers clean. The door has a latch mechanism, which is typically adapted to be engaged and operated automatically via robots or other automatic machinery. The latch mechanism is largely contained within hollow spaces within the door. The hollow spaces within the door, and other interior door features, make cleaning the FOUP door difficult, using conventional techniques. The hollow areas trap water or other cleaning fluids. Accordingly, improved apparatus and techniques are needed for cleaning FOUP doors.
Box carriers have been successfully cleaned in centrifugal cleaners. See, for example, U.S. Pat. No. 5,738,128, incorporated herein by reference. In these centrifugal cleaners, the box is loaded onto a rotor, with the open top or front side of the box facing radially outwardly from the rotor. The box is then sprayed with cleaning fluids, and then with drying gases, while the rotor turns. Centrifugal force helps to remove cleaning fluids from the box, to help dry it. While these techniques have worked well for different types of boxes, FOUP carriers have larger five-sided boxes. Accordingly, FOUP boxes cannot be readily loaded onto, or securely held in place on, a conventional rotor in a centrifugal box cleaner. Accordingly, an improved centrifugal box cleaner is needed for use with FOUP boxes.
As FOUP carriers include a box and a separate door, which must both be cleaned, but require different cleaning techniques, a system for efficiently cleaning both of these components of a FOUP container is also needed.